The subject matter described herein relates generally to wind turbines and, more particularly, to a pre-stressed stiffening system for a wind turbine generator frame.
Known wind turbines convert the kinetic energy of wind into electrical energy. Wind turbines include one or more blades that rotate when oncoming wind strikes the blades. The flow of wind over the wind turbine blades generates lift, induces rotation, and provides torque to generate power.
The torque generated by the rotation of the wind turbine blades is used to turn a shaft of a generator, that in turn generates electricity. The generator is supported by a frame disposed at or near the top of a tower. As the blades are struck by winds of variable speed and direction, forces of varying magnitudes are transmitted from the blades to the generator, and in turn the generator frame. Over time, these forces may lead to fatigue failure of the generator frame in the form of cracks or other similar defects. Since the generator frame is disposed at or near the top of the tower, the weight of the generator frame is a primary concern. As such, merely increasing the thickness of the generator frame (and correspondingly increasing the mass of the generator frame) is not an efficient solution to the fatigue failure of the generator frame. Accordingly, a solution is needed to prevent fatigue failure of generator frames that does not significantly increase the mass of the generator frames.